The invention relates to protective coatings for components of disc drive data storage systems. In particular, the invention relates to protective coatings for magnetic materials used in disc drive systems used for the storage and/or retrieval of data, including, for example, magnetic read/write heads and magnetic discs.
Advances in many technologies have created enhanced demands on materials used in the production of a variety of devices. Specifically, miniaturization has decreased tolerance levels while increasing performance requirements. Furthermore, coating technology has become extremely important since coatings can be used to alter the surface properties of the composite while maintaining desirable properties of the underlying substrate. In particular, thin coatings can serve to protect the underlying substrate from a variety of assaults.
Magnetic and optical-magnetic data storage devices generally use data storage discs and magnetic heads for reading and/or writing. In use, the heads xe2x80x9cflyxe2x80x9d just above the disc while the disc is spinning at a rapid rate. The read/write head generally includes an air bearing surface, which faces the disc surface. As the disc rotates, the disc drags air along the air bearing surface. As the air passes along the air bearing surface, the air pressure between the disc surface and the air bearing surface creates a hydrodynamic lifting force that causes the slider or head to lift in relation to the disc surface. The hydrodynamic lift and corresponding fly height are affected by the speed of rotation of the disc, the design of the air bearing surface of the read/write head and the preload force supplied to the head by the gimbal assembly supporting the head.
Read/write heads generally use magnetic transducers to read and/or write data from a magnetic data disc. Heads with magneto-resistive elements can also be used for asperity detection to identify imperfections on the surface of a rotating disc by identifying changes in electrical resistance after the head contacts a bump or imperfection on a disc surface. If unacceptable imperfections are detected, the disc can be smoothed or discarded. Similarly, heads with magnetic transducers can be used in combination magneto-optical disc storage systems.
Disc drives for data storage can use one or more discs with a magnetizable medium for the storage of information. The magnetic medium generally is formed by a relatively thin magnetic layer on a non-magnetic substrate. Typically, the data is stored at specific locations along concentric data tracks. The disc drive assemblies for magnetic data storage include head gimbal assemblies aligned with the disc surface. The head/gimbal assemblies support transducers, such as magnetoresistive elements, for reading data from and writing data to the data tracks near the disc surface. Information is stored in the magnetic media within the data storage zones.
Intermittent contact between the head and the disc surface causes wear of the disc surface and the head. To protect the disc surface and/or the head from wear and corrosion, overcoats can be placed over the magnetic medium on the disc surface and/or the head surface. Preferred overcoats reduce wear, friction and oxidation while maintaining proper hydrodynamic interaction between the head and the disc surface during rotation and during take-off and landing. Protective overcoats also protect the head during processing and fabrication.
To obtain higher storage densities on the disc surface, fly heights between the read/write head and the disc surface are being reduced. Reducing the fly height improves the magnetic interaction between the head and the disc surface to allow correspondingly higher data storage densities. Thus, it is important that protective coatings are thin enough not to excessively increase the effective distance between the magnetic transducers of the head and the magnetic materials near the disc surface.
Carbon coatings have been used to form protective layers on substrates. The coating, however, increases the spacing between the surface and the underlying substrate. Thus, for example in the production of magnetic discs, any performance improvement resulting from a reduction in fly height can be countered by the presence of protective coatings and the like that result in an increased distance of the magnetic medium and the disc surface.
In a first aspect, the invention pertains to a disc drive data storage system comprising a magnetic material and a means for protecting the surface of the magnetic material.
In a further aspect, the invention pertains to a disc drive data storage system comprising a magnetic material having a coating surface of a material selected from the group consisting of metals, semiconductors and mixtures thereof. The coating surface has an approximate monolayer of fullerene molecules bonded to the coating surface with a bond strength greater than fullerene-fullerene intermolecular bond strength.
In another aspect, the invention pertains to a method for protecting a surface of a magnetic material in a disc drive data storage system. The method includes depositing an approximate monolayer of fullerene molecules on the surface of the magnetic material. The surface comprises a material selected from the group consisting of metals, semiconductors and combinations thereof, and the surface is substantially free of contaminants.
In an additional aspect, the invention pertains to another method for protecting a surface of a magnetic material in a disc drive data storage system. The method includes depositing fullerene molecules on a surface of the magnetic material under ultrahigh vacuum with a pressure no more than about 1xc3x9710xe2x88x927 torr.